Captain Jack Harkness reunites with the Doctor and the TARDIS is thrown out of control to the end of the universe. They meet Professor Yana, who is working on a means to save the remnants of humanity while a race known as the "Futurekind" attempt to thwart his plans.

Doctor	David Tennant (Tenth Doctor)
Companions	Freema Agyeman (Martha Jones)
	John Barrowman (Jack Harkness)
Writer	Russell T. Davies
Director	Graeme Harper
Executive Producer(s)	Russell T. Davies Julie Gardner
Production code	3.11
Series	Series 3
Originally broadcast	16 June 2007
Preceded by	"Blink"
Followed by	"The Sound of Drums"

• This is Derek Jacobi's third involvement in Doctor Who and second time playing the Doctor's nemesis. The first was in the September 2003 audio drama Deadline,^[3] where he played a screenwriter who believes himself to be the Doctor. The second was several months later, in the webcast Scream of the Shalka, where he played an android version of the Master.^[4] David Tennant also had a minor, uncredited role in Scream of the Shalka.
• John Bell is a nine-year-old who won a Blue Peter competition to appear in this episode.^[5]